Agricultural Production:
Yellow tomatoes are commonly grown by home gardeners for their unique appearance and less acidic, sweet taste. The tomatoes harvested from such seed sources are very tender and soft. The plants are generally indeterminate in growth habit with staggered fruit set.
More than 95% of tomatoes for processing in the U.S. are grown in California. The planting begins in January in the southern part of San Joaquin Valley and continues until late May in the northern parts of the San Joaquin Valley. Most of the planting takes place by direct seeding. Less than 15% of the total acreage for processing tomatoes is transplanted with the seedlings grown in the greenhouses.
Temperatures vary widely during planting, growing and flowering time periods. For example, tomato seeds are sown in Bakersfield area in January when the daytime temperature could range 45-60° F. and nights are often below 32° F. These seeds emerge, grow, flower and set fruits from mid-February to the first week in July when temperatures gradually climb to over 100° F. in daytime and 65-75° F. at night.
In the central parts of the San Joaquin valley tomato seeds are sown in March and are harvested in August. Normally, the daytime temperature ranges from 60-70° F. in March to 85-103° F. in July and August. In Stockton, Sacramento and northern areas, the seeds are sown in April-May and harvested in September. Here the daytime temperatures range from 90-100° F. throughout the entire growing season, often with drastic cooling at night. Thus, the tomato growing industry requires tomato varieties that grow, flower and set fruit in variable environmental conditions. Yellow tomatoes from other sources do not have this ability to produce commercial yields under these conditions. Most of them abort flowers, and therefore do not produce significant yields, at high temperatures.
Last year nearly 11 million tons of tomatoes were grown in California on approximately 300,000 acres, and were harvested and processed from the first week in July to the last week in September. All of these tomatoes were red in color. These tomatoes were mechanically harvested and then transported by open bed trucks in 25-ton loads to the processing plants. Average distance between the field of production and processing plant in California is 135 miles. The tomatoes have to be very firm at full maturity and free from peduncles (stems) in order not to puncture other tomatoes in the truck. These trucks wait in the open yards under blazing sun for up to 40 hours before the tomatoes get processed. Yellow tomatoes typically are too soft and tender to survive this ordeal intact. Moreover, yellow tomatoes are typically susceptible to sunburn damage.
Mechanical harvesting involves a single harvest that destroys the tomato plants. In mechanical harvesting, concentrated fruit setting ability, concentrated maturity and ability of ripe fruit to store on the plant are critical factors that determine the efficiency of machine harvest. Small plant size and short internodes with profuse flowering are contributing factors for concentrated fruit set. In addition, the fruits have to be very firm to withstand the rigors of machine harvesting. Yellow tomatoes from other sources do not have the structural components necessary for machine harvesting.
Processing in the Factory:
Tomato products are manufactured in two principal categories, peeled and concentrated. Peeling for canned tomatoes is performed by treating the tomatoes with either steam or lye (NaOH). For steam peeling, tomatoes are scalded in live steam long enough to loosen the skin. For an efficient tomato peeling operation, it is essential that the skin be completely loosened.
Chemical peeling of tomatoes is accomplished by a 11-19% solution of Caustic soda or sodium hydroxide, also called lye. A high temperature (190-210° F.) solution of caustic soda dissolves the waxy cuticular layer of the skin of tomatoes and quickly disrupts outer tissues of the fruit while leaving the inner flesh untouched.
Only tomatoes with very firm fruit walls can be subjected to high pressure steam and/or caustic soda for peeling. Tomatoes with softer tissues do not remain intact and tend to lose significant weight during the process. Tomatoes retaining stems after harvest will not allow complete separation of the skin from the fruit walls. In addition, a significant amount of tomatoes are made sliced and diced. The fruit wall structure is extremely critical for finished product quality and commercial efficiency of sliced and/or diced tomatoes.
More than 65% red tomatoes are processed into concentrated products such as puree, sauce and paste. Tomato juice is made by grinding whole tomatoes in high temperature juice to maintain pectins and other chemical constituents of tomatoes that contribute to viscosity of juice. Purees range from light to heavy with soluble solids ranging from 8-10% for light and 11.3-15% for heavy.
Paste is generally 32% soluble solids. Juice contains 4-5.5% soluble solids. Only the tomatoes having pH of 4.3 and below (measured in fresh or cooked juice) at full maturity are suitable for processing. Most yellow tomatoes have pH values higher than 4.3, which makes them poor candidates for processing.
Ketchup, Mexican salsa, pasta sauce, pizza sauce, barbecue sauce, cocktail sauce, tomato based salad dressings and other products are manufactured from paste. Color and flavor retention are absolutely essential during the concentration process starting with the juice at 5% soluble solids and reaching paste at 32% soluble solids. Reconstituted products from paste need to have tomato taste and color for consumer acceptance.
The following traits in tomato varieties are useful for transporting and processing of tomatoes. This set of traits is designated “Processing Quality Factors” (or PQFs).                1. Holding ability of the fruit on the plant, i.e., firm fruit walls and thick skin, no decay of older fruits, no germination of seeds in the older fruits, no breakdown of sugars inside the older fruits, and no fermentation within the older fruit.        2. Firmness of the fruits to withstand mechanical harvesting and transportation as well as storage under open sky conditions at 100° F. without significant breakdown and disease development.        3. Firmness of the fruits to withstand high pressure steam (e.g., 15-30 psi at 225°-250° F.) and /or application of chemicals (e.g., 11-19% NaOH at 190°-210° F.) to peel the skin off the fruits.        4. Firmness of the fruits to withstand high pressure steam for cooking as whole tomatoes.        5. Firmness of the fruits to withstand cutting to make diced tomato products.        6. Firmness of the sliced and diced tomato products to withstand cooking with high pressure steam.        
The prior art lacks a yellow tomato that has these traits. The present invention addresses this and other issues.